Practical implications of GPR investigation using 3D data reconstruction and transmission tomography

Non-destructive investigation using ground penetrating radar is becoming more popular in the inspection of civil structures. Currently, traditional 2D imaging is used as a preliminary tool to fi nd possible areas of interest for more detailed inspection, which can be accomplished by more advanced techniques like 3D image reconstruction or tomography. In this paper, a general overview of the work done at University of Minho regarding these techniques is presented, together with their limitations and advantages over typical radargrams, with implications for civil engineering applications. For this purpose, data acquisition on two large masonry walls and one large concrete specimen have been carried out, using refl ection mode, 3D reconstruction and transmission tomography. The specimens have been specially built for non-destructive inspection techniques testing, incorporating different materials and internal voids. Radar tomography and 3D image reconstruction techniques provided much more detailed information about structural integrity and shapes and location of the voids, when compared to 2D imaging originally used for potential target identification.Fundação para a Ciência e a Tecnologia (FCT) - POCTI SFRH/BD/6409/2001"Sustainable Bridges" European project - FP6-PLT-0165